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Explanation:
The symbol or mu represents the population mean, which is a parameter.
The symbol or sigma represents the population standard deviation, which is also a parameter. The same goes for the symbol p, without any hat on top, as it is the population proportion.
If something represents a population data item, then it's automatically a parameter. It might help to think both words "population" and "parameter" start with the letter P.
Based on those previous paragraphs, we can rule out choices A, D and E. Those three items are parameters. This leaves <u>choices B and C</u> as our final answers.
or xbar is a sample statistic, and it represents an estimate of the population mean. Similarly,
or p-hat is the sample proportion and it represents an estimate of the population proportion. These are considered unbiased estimators.
Another example of an unbiased estimator is the variable s which represents the sample standard deviation and it estimates the value of sigma. All of these estimators have one thing in common: they are based on a sample, which in turn tries to predict what the corresponding population value is. In other words, the statistic's job is to estimate the parameter.
Below is a reference table for all of the items mentioned.
